As oil is lighter than water skimming devices for separating oil from a heavier body of liquid, such as water, are available for collecting and removing the surface oil from the body of liquid. Such devices are commonly used to recover oil from machine tool coolants, and may also be employed to recover tramp oil and remove oil from large bodies of water as occurs during an oil spill.
It has been discovered that oil and similar floating material can be removed from the surface of a body of water by the use of an endless belt, web, or rope which passes through the liquid surface wherein the oil will adhere to the rising belt or rope and can be removed therefrom by scraping or squeezing actions. United States patents disclosing oil separating devices of the endless belt or web type are shown in U.S. Pat. Nos. 3,314,545; 3,508,663; 3,640,394; 3,709,369; 4,154,683; 4,274,957; 4,652,372 and 4,582,604. The devices shown in these patents employ pressure rollers or scrapers to remove the oil from the belt or web, and while the prior art devices are capable of collecting oil from the surface of a liquid the efficiency of operation is low, and problems are encountered in effectively removing the oil from the belt or strand and collecting the same without reintroducing a significant amount of oil back into the body of liquid being treated.
Flexible belt, web and strand oil skimmers have the advantage over oil removers utilizing rotating discs which are partially submerged in the liquid in that the flexibility of belts and strands permits the apparatus to be relatively concise in configuration and adaptable to various configurations of installation, particularly with respect to accommodating machine tool configurations when removing oil from cutting tool coolants. However, belt and strand skimmers using doctor and scraper blades to remove the oil from the moving belt or web wear the belt requiring frequent belt and blade replacement, and such devices require frequent maintenance attention for efficient operation.
Belt, web and strand skimmers utilizing the pressure of rollers to squeeze the oil from the belt do not wear the belt to the extent of a scraper blade, but the use of rollers creates a "puddle" at the entrance of the belt into the rollers and as such roller type skimmers employ horizontally disposed rollers it is difficult to dissipate or drain off the puddle efficiently which causes a relatively high percentage of oil to remain on the belt adversely affecting the efficiency of the apparatus.
It is an object of the invention to provide apparatus of the oil removing or skimming type utilizing a flat belt or web by removing the oil from the belt by rollers and yet the oil removed by the rollers is quickly drained from the location of oil removal to produce high efficiency oil removal.
A further object of the invention is to provide oil skimming apparatus of the endless belt type wherein minimum belt wear occurs while high oil removal efficiencies are obtained in apparatus which requires a minimum of maintenance and servicing.
Another object of the invention is to provide oil skimming apparatus of the endless belt type wherein oil is removed from the belt by rollers and the rollers are substantially vertically oriented wherein the oil removed from the belt quickly falls under gravitational force away from the belt and roller.
An additional object of the invention is to provide oil skimming apparatus of a concise configuration which may take a portable form and may be readily employed in a wide variety of installations, and is particularly suitable for removing oil from the coolant of machine tools.
A further object of the invention is to provide oil skimming apparatus of concise configuration wherein the operating components may be readily vertically adjusted relative to a portable reservoir for collecting the removed oil.
Another object of the invention is to provide oil skimming apparatus of the endless belt type wherein removal and installation of the belt is readily accomplished requiring no special skill on the part of the operator.
The apparatus of the invention includes a frame which may be associated with an oil receiving reservoir. The frame includes a housing vertically mounted upon and adjustable above the reservoir and the housing supports an electrical motor driven primary cylindrical roller having a vertically oriented axis of rotation. The lower end of the roller is free and unsupported whereby an endless belt may be readily slipped under the roller and passed thereabout.
A plurality of pressure rollers having axes of rotation parallel to the vertical primary roller axis are located upon opposite sides of the primary roller and are biased by springs toward the primary roller maintaining the belt thereon and compressing the belt to the primary roller.
The belt is of such length that its lower portion extends below the primary roller and naturally twists to define a reversing loop at its lowermost portion having a horizontal axis defining the reversal of direction of the belt. A weight roller is preferably located in the belt reversing loop to help maintain the belt taut. The lower belt portion is submerged in the body of liquid being treated and as the belt moves upwardly through the surface of the body oil on the body surface will adhere to the belt and be removed by the compression of the belt between the primary roller and the pressure rollers.
A collection receptacle is located directly below the primary and pressure rollers receiving the oil removed from the belt. The collection receptacle includes an outlet in communication with the reservoir and as the frame housing and its associated components are vertically adjustable relative to the reservoir the conduit connection between the receptacle and reservoir telescopes to accommodate the vertical position of the receptacle.
Preferably, the motor circuit includes a timer and other controls wherein the operation of the apparatus may be regulated so that the oil removing procedure need occur no longer than necessary to accommodate a particular situation thereby achieving maximum belt life and efficiency of power consumption.
As the axes of rotation of the primary and pressure rollers are vertical, the "puddle" of oil that occurs as the belt enters the primary and initial pressure rollers is quickly drained away by gravity into the collection receptacle, and the use of two pressure rollers, both being vertically oriented, quickly removes a very high percentage of the oil from the belt minimizing the amount of oil adhering to the belt for reintroduction into the liquid and producing a very high efficiency of operation.
No guide rollers are necessary to achieve the twisting of the belt which occurs between the primary and weight rollers, and the apparatus of the invention produces a minimum of belt wear assuring low maintenance and a low cost of operation.